JP2011020026A - Drying tower - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent the flow of sulfuric acid toward a rear stage while being entrained in gas, and to suppress the increase of pressure loss. <P>SOLUTION: The drying tower is provided with a sulfuric acid supply nozzle 1 for bringing gas A into contact with sulfuric acid, and a gas-liquid separation part 3 disposed in the downstream of the gas flow from the sulfuric acid supply nozzle 1 and separating the gas A from the sulfuric acid entrained in the gas A. The gas-liquid separation part 3 has demisters 3b, 3c packed with packings in the gas A flow path in this order. Thus, sulfuric acid entrained in the gas A is sufficiently collected by the demisters 3b, 3c to surely prevent the flow of the sulfuric acid toward the rear stage while being entrained in the gas A. By setting a packing density in the demister 3b lower than that in the demister 3c, deposit such as simple substance of sulfur can be coarsely taken out by the demister 3b on the upstream side of the gas flow causing little impairment of gas permeability due to the lower packing density, thus causing little impairment of gas permeability in the demister 3c downstream of the gas flow, to suppress the increase of pressure loss. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a drying tower for removing moisture in a gas.

  Conventionally, concentrated sulfuric acid is allowed to flow from the top of the tower to the bottom of the tower, and a wet gas is flowed from the bottom of the tower to the top of the tower to face the wet gas. There is known a drying tower for removing moisture in the inside (see, for example, Patent Document 1). In such a drying tower, gas-liquid separation means for separating the gas and the concentrated sulfuric acid accompanying the gas is provided in order to collect the concentrated sulfuric acid so that the concentrated sulfuric acid is not entrained by the gas and going to the subsequent stage. It is widely done.

JP 2005-288431 A

  Here, in the drying tower as described above, it is desired to reliably prevent sulfuric acid from being entrained in the gas and going to the subsequent stage.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a drying tower capable of reliably preventing sulfuric acid from being entrained in a gas and going to the subsequent stage.

  Here, as a result of intensive studies, the inventors of the present invention have used a gas-liquid separation means in the drying tower as described above for a packing member filled with a predetermined packing to collect sulfuric acid accompanying the gas. It has been found that by providing a plurality of channels in the flow path, sulfuric acid can be sufficiently collected by these filling members and the above-described problems can be solved.

  On the other hand, when the gas introduced into the drying tower contains, for example, a sulfur compound such as hydrogen sulfide, precipitates such as elemental sulfur are deposited in the drying tower. According to the gas-liquid separation means as described above, the problem that the multistage filling member collects precipitates such as simple sulfur, impairs the air permeability, and consequently increases the pressure loss. I found it. Therefore, as a result of further research to solve this problem, the present inventors have determined the packing density of the packing in the packing member on the upstream side of the gas flow in the gas-liquid separation means as described above. It has been found that an increase in pressure loss can be suppressed by making the packing density lower than the packing density of the packing member on the downstream side of the gas flow.

  Therefore, the drying tower according to the present invention is a drying tower for removing moisture in the gas, gas-liquid contact means for bringing the gas into contact with sulfuric acid, gas disposed downstream of the gas-liquid contact means and gas In a drying tower provided with a gas-liquid separation means for separating sulfuric acid entrained by gas, the gas-liquid separation means is a gas flow through a packing member filled with a filler to collect sulfuric acid accompanying gas. The plurality of filling members are characterized in that the filling member on the upstream side of the gas flow has a lower packing density than the filling member on the downstream side of the gas flow.

  According to such a drying tower, since the gas-liquid separation means has a plurality of filling members in the gas flow path, the sulfuric acid accompanying the gas is sufficiently collected by the plurality of filling members, and the sulfuric acid is accompanied by the gas. It is reliably prevented from going to the latter stage. Further, according to such a drying tower, the packing member on the upstream side of the gas flow has a lower packing density than the packing member on the downstream side of the gas flow. Therefore, even if a precipitate such as simple sulfur is collected, the air permeability is not easily lost. Then, the gas that has passed through the gas flow upstream side filling member is roughly collected and removed (roughly removed) by deposits such as elemental sulfur by the gas flow upstream side filling member. Precipitates such as simple sulfur reaching the filling member on the downstream side of the flow are reduced, and the air permeability of the filling member on the downstream side of the gas flow is not easily impaired. Therefore, an increase in pressure loss is suppressed.

  Here, it is preferable to provide a cleaning means for spraying sulfuric acid on the filling member to wash the filling member. According to this configuration, even when precipitates such as simple sulfur are collected on the filling member and the air permeability of the filling member is impaired, sulfuric acid is sprayed on the filling member by the cleaning means. Since it is washed, precipitates such as elemental sulfur collected on the filling member are removed, and the air permeability of the filling member is restored. As a result, an increase in pressure loss is further suppressed.

  The filling is preferably made of plastic. Conventionally, as a filling member in the gas-liquid separation means, a material in which a wire mesh made of stainless steel is filled as a filling material is widely used. According to such a conventional filling member, Ni (nickel) contained in stainless steel is used. ) Acted as a catalyst for the production of elemental sulfur and promoted the precipitation of elemental sulfur in the drying tower. On the other hand, as described above, by constituting the filling material from plastic, precipitation of elemental sulfur is greatly suppressed as compared with the case where the filling material contains Ni.

  Thus, according to the present invention, it is possible to reliably prevent sulfuric acid from being entrained in the gas and proceeding to the subsequent stage, and to suppress an increase in pressure loss.

It is a block diagram which shows the drying tower which concerns on this embodiment.

  Hereinafter, a preferred embodiment of a drying tower according to the present invention will be described with reference to FIG. FIG. 1 is a configuration diagram showing a drying tower according to the present embodiment.

A drying tower 10 shown in FIG. 1 is applied to a sulfuric acid production facility for producing sulfuric acid from a gas containing SO _2. Water in the gas is removed, and the gas from which the water has been removed is transferred to a subsequent apparatus. To supply. Note that the gas in the present embodiment is a high-concentration SO ₂ -containing gas generated when regenerating the carbonaceous adsorbent that has adsorbed SO ₂ in the exhaust gas in an exhaust gas treatment facility using a carbonaceous adsorbent such as activated carbon. Including sulfur compounds such as SO ₂ , H ₂ S and COS.

  The drying tower 10 is configured such that the gas A is introduced from the bottom of the tower to the inside and heads to the top of the tower, and sulfuric acid is sprayed and supplied downward to the gas A that is introduced into the inside and flows upward. A sulfuric acid supply nozzle (gas-liquid contact means) 1 to be brought into contact with the sulfuric acid supply nozzle 1 is arranged upstream of the gas flow (downward in the drawing) to increase the contact area between the sulfuric acid supplied from the sulfuric acid supply nozzle 1 and the gas A. Circulation for supplying the sulfuric acid supplied to the sulfuric acid supply nozzle 1 again with the packed bed 2 and the sulfuric acid supplied to the gas A from the sulfuric acid supply nozzle 1 and falling through the packed bed 2 and stored in the bottom of the drying tower 10. A line 1, a pump 1 a disposed in the circulation line L 1 to form a flow of sulfuric acid from the bottom of the drying tower 10 toward the sulfuric acid supply nozzle 1, and a sulfuric acid from the sulfuric acid supply nozzle 1 also disposed in the circulation line L 1. The supply of And a gas-liquid separator (gas-liquid) for separating the gas A and the sulfuric acid accompanying the gas A, which is arranged downstream of the gas flow (upward in the figure) from the sulfuric acid supply nozzle 1. Separation means) 3 is provided.

  The gas-liquid separation unit 3 has three demisters (filling members) filled with a filler to collect sulfuric acid accompanying the gas A in the flow path of the gas A. A demister 3a, a demister 3b, and a demister 3c are formed from the gas flow upstream toward the gas flow downstream. The fillings of these demisters 3a to 3c are obtained by weaving fine wires made of plastic such as polypropylene in a lattice shape, for example.

  The demister 3a is arranged on the most upstream side of the gas flow among the three demisters 3a to 3c downstream of the sulfuric acid supply nozzle 1, and the demister 3b is located at a predetermined distance from the demister 3a on the downstream side of the gas flow of the demister 3a. The demister 3c is disposed so as to overlap the demister 3b on the downstream side of the gas flow of the demister 3b.

  Here, the packing density of the packing material in the demister 3a and the packing density of the packing material in the demister 3b are substantially the same. In particular, in this embodiment, the packing density of the packing material in the demisters 3a and 3b is It is set lower than the packing density of the packing in the demister 3c. In addition, the packing density of the packing material in the demisters 3a to 3c is, for example, the roughness of the grid composed of fine lines as the packing material. In this case, the packing density is lower as the eyes are rougher.

  The demisters 3a to 3c are provided with spray nozzles for washing the demisters 3a to 3c with sulfuric acid. Specifically, two spray nozzles (cleaning means) 4aa and two spray nozzles (cleaning means) 4ab clean the demister 3a between the demister 3a and the sulfuric acid supply nozzle 1 in the vicinity of the gas flow upstream of the demister 3a. These spray nozzles 4aa and 4ab spray sulfuric acid upward from the gas flow upstream toward the demister 3a. Further, between the demister 3a and the demister 3b, two spray nozzles (cleaning means) 4ba and two spray nozzles (cleaning means) 4bb are for cleaning the demister 3a in the vicinity of the gas flow downstream of the demister 3a. These spray nozzles 4ba and 4bb spray sulfuric acid downward from the gas flow downstream toward the demister 3a. Further, in the vicinity of the gas flow downstream of the demister 3c, two spray nozzles (cleaning means) 4ca and two spray nozzles (cleaning means) 4cb clean the demister 3c and also clean the demister 3b via the demister 3c. These spray nozzles 4ca and 4cb spray sulfuric acid downward from the gas flow downstream toward the demister 3c.

  Each of these spray nozzles has a branch branched from the circulation line L1 so as to supply sulfuric acid supplied to the gas A from the sulfuric acid supply nozzle 1 and in contact with the gas A and stored at the bottom to the spray nozzle. The lines L2 are connected to each other, so that each of the spray nozzles uses sulfuric acid supplied to the gas A from the sulfuric acid supply nozzle 1 and recovered in contact with the gas A.

  Here, the lines connecting the spray nozzles 4aa and 4ab and the branch line L2 are provided with valves 5aa and 5ab, respectively, and the opening and closing of these valves 5aa and 5ab are controlled independently. Both the spray nozzles 4aa and 4ab can be used at the same time, or either one can be selected and used. Similarly, valves 5ba and 5bb (5ca and 5cb) are provided on lines connecting the spray nozzles 4ba and 4bb (4ca and 4cb) to the branch line L2, respectively. These valves 5ba and 5bb ( By independently controlling the opening and closing of 5ca and 5cb), both of the spray nozzles 4ba and 4bb (4ca and 4cb) can be used simultaneously, or either one can be selected and used.

  According to the drying tower 10 configured as described above, the gas A introduced into the drying tower 10 is supplied with sulfuric acid by the sulfuric acid supply nozzle 1 and comes into contact with the sulfuric acid, and the water in the gas A is absorbed by the sulfuric acid. Removed. Thereafter, the gas A from which the moisture has been removed passes through each of the demisters 3a to 3c of the gas-liquid separator 3, whereby sulfuric acid accompanying the gas A is collected in the demisters 3a to 3c, and the gas A and the gas A The sulfuric acid entrained in A is separated. Then, the gas A from which the sulfuric acid has been separated and removed by the gas-liquid separator 3 is discharged to the outside of the drying tower 10 so as to be supplied to the subsequent apparatus.

  And according to the drying tower 10 of this embodiment, since the gas-liquid separation part 3 has several demisters 3a-3c, the sulfuric acid accompanying gas A is fully collected by these demisters 3a-3c, In particular, since the sulfuric acid accompanying the gas A is sufficiently collected by the demister 3c having a relatively high packing density of the packing material, it is possible to reliably prevent the sulfuric acid from being accompanied by the gas A and going to the subsequent stage.

Further, according to the drying tower 10 of the present embodiment, the demister 3b has a packing density lower than that of the demister 3c on the downstream side of the gas flow, so that the flow path of the gas A in the demister 3b is relatively low. For this reason, clogging hardly occurs even if precipitates such as simple sulfur produced from sulfur compounds such as H ₂ S are collected, and air permeability is not easily impaired. Since the gas A that has passed through such a demister 3b is roughened by deposits such as simple sulfur by the demister 3b, precipitates such as simple sulfur reaching the demister 3c on the downstream side of the gas flow are reduced. The demister 3c having a packing density higher than that of the demister 3b is also less likely to be clogged and the air permeability is not easily impaired. Therefore, according to the drying tower 10 of this embodiment, an increase in pressure loss can be suppressed.

  Further, in the drying tower 10 of the present embodiment, the demister 3a filled with the packing with substantially the same packing density as the demister 3b is disposed upstream of the gas flow of the demister 3b. The deposited precipitates of simple sulfur are first roughly removed by the demister 3a. For this reason, clogging is less likely to occur in the demisters 3b and 3c.

  Also, when the demisters 3a to 3c collect precipitates such as simple sulfur, even if these or some of the demisters are clogged and the air permeability is impaired, sulfuric acid is directed toward the demisters by the spray nozzles. Is sprayed and the demisters 3a to 3c are washed, so that precipitates such as simple sulfur collected in the demisters 3a to 3c are removed, and the clogging of the demisters 3a to 3c is eliminated. Breathability is restored. In particular, the demister 3a is arranged at the most upstream side of the gas flow among the demisters 3a to 3c, thereby collecting the largest amount of precipitates such as elemental sulfur, but spray nozzles 4aa, 4ab, 4ba, 4bb on both sides thereof. Since these spray nozzles 4aa, 4ab, 4ba, 4bb are sprayed with sulfuric acid and washed from both sides, the collected precipitates of elemental sulfur and the like are preferably removed, clogging is eliminated, and air permeability is eliminated. Is recovered. Therefore, an increase in pressure loss can be further suppressed. As a result, the demisters 3a to 3c can be stably operated over a long period of time without taking out the demisters 3a to 3c from the drying tower 10 and washing them or replacing them.

  In each spray nozzle, sulfuric acid supplied from the sulfuric acid supply nozzle 1 to the gas A and brought into contact with the gas A is used. Therefore, when washing the demisters 3a to 3c, it is necessary to introduce new sulfuric acid from the outside. And cost can be reduced.

  Further, the spray nozzles 4aa, 4ab (4ba, 4bb, 4ca, 4cb) are used by sequentially selecting and controlling one of the sides, so that a region on one side of the demister 3a (3b, 3c) (in the right half of the figure). This can be cleaned by spraying sulfuric acid alternately on the area) and the area on the other side of the demister 3a (3b, 3c) (the left half area in the figure). As a result, compared with the case where sulfuric acid is sprayed simultaneously on the entire surface of the demister 3a (3b, 3c), the flow path of the gas A is less likely to be blocked and pressure loss is less likely to occur.

  Furthermore, since the filling material filled in each of the demisters 3a, 3b, 3c is made of plastic, the precipitation of elemental sulfur is greatly suppressed as compared with the case where the filling material contains Ni.

  Note that the spraying timing of sulfuric acid in the spray nozzles 4aa and 4ab, the spray nozzles 4ba and 4bb, and the spray nozzles 4ca and 4cb may or may not be the same. In addition, these spraying times may be wrapped with each other or may not be wrapped.

  Further, each spray nozzle can spray sulfuric acid at a predetermined time interval or by an increasing tendency of pressure loss of the demisters 3a to 3c under the control of a control device (not shown). The part may be sprayed with sulfuric acid by manual control.

  In addition, the number of installed spray nozzles is not limited to the number of installed nozzles in the above-described embodiment, but may be an arbitrary number of installed nozzles depending on the size of the drying tower 10 and the demisters 3a to 3c, a desired cleaning range, and the like. it can.

  The means for cleaning the demisters 3a to 3c is not limited to the spray nozzle that sprays sulfuric acid, but can supply the sulfuric acid to the demisters 3a to 3c and remove single sulfur collected by the demisters 3a to 3c. Well-known cleaning means.

  Moreover, in the said embodiment, although each demister 3a-3c shall be filled with the filler which woven the thin wire | line in the grid | lattice form, it is not restricted to this, For example, as what was filled with the irregular filling Also good.

  Further, the present invention can be applied to two or more demisters, not limited to three.

  DESCRIPTION OF SYMBOLS 1 ... Sulfuric acid supply nozzle (gas-liquid contact means), 1a ... Pump, 1b, 5aa, 5ab, 5ba, 5bb, 5ca, 5cb ... Valve, 2 ... Packing bed, 3 ... Gas-liquid separation part (gas-liquid separation means), 3a, 3b, 3c ... demister (filling member), 4aa, 4ab, 4ba, 4bb, 4ca, 4cb ... spray nozzle (cleaning means), 10 ... drying tower.

Claims (3)

A drying tower for removing moisture in the gas, gas-liquid contact means for bringing the gas into contact with sulfuric acid, gas disposed downstream of the gas-liquid contact means, and sulfuric acid accompanying the gas, In a drying tower provided with a gas-liquid separation means for separating
The gas-liquid separation means has a plurality of filling members filled with a filler to collect sulfuric acid accompanying the gas in the gas flow path,
The drying tower characterized in that the packing density of the packing is lower in the packing member on the upstream side of the gas flow than in the packing member on the downstream side of the gas flow.   The drying tower according to claim 1, further comprising a cleaning unit that sprays sulfuric acid onto the packing member to clean the packing member.   The drying tower according to claim 1 or 2, wherein the packing is made of plastic.

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